New Citizen’s Radiocommunication Development and Construction of Equipment

November 13, 1946

The Commission is interested in securing the cooperation of manufacturers and others in preparing technical requirements for equipment to be used in the Citizen’s Radiocommunication Service.   As a starting point for conferences between manufacturers and the Commission’s Staff, material dealing with technical requirements has been prepared and is attached hereto, bearing the designation “Requirements ant Type Approval Tests for Equipment to be used in Citizens’ Radiocommunication Service.”   The principal objective of such requirements and type-approval tests is to establish a uniform regulatory procedure whereby specific types of transmitting equipment constructed by manufacturers for ultimate use in this service by the general public would be formally approved by the Commission for the purpose of thereafter authorizing their use under appropriate radio station licenses.   Such “type-approval” would be contingent upon the production model meeting all of these technical requirements after inspection and test by the Commission’s Engineering Department.

The attachment hereto is not to be regarded as proposed rules but as a preliminary proposal designed to organize discussion and comment.   Comments regarding the attachment, suggestions with respect to technical requirements, and information relating to the development or operation of equipment in the frequency band 460-470 Mc would be appreciated.   They should be forwarded to the Commission at Washington, D.C. as soon as possible, but, in any event, not later than December 31, 1946. Requests for consultation with the Commission’s Staff are invited. Such requests should include information as to the most desirable time and place for conferences.

On July 18, 1946, the Commission approved, transmitted to the State Department, and made public, its latest “Table of Allocations from 25,000 to 30,000,000 kc”.   Included therein is the band 460-470Mc which thereby is allocated in the United States to “Non-Government Citizens’ Radio” and proposed internationally for “Fixed and Mobile Service”.   The stated condition of this allocation is that it is established “on an experimental basis pending adequate showing as to need and technical requirements”.

The possible uses of this service are as broad as the imagination of the public and the ingenuity of equipment manufacturers can devise.   The citizens radiocommunication band can be used, for example, to establish a physicians’ calling service, through which a central physicians’ exchange in each city can reach doctors while they are en route in their cars or otherwise not available by telephone.   Department stores, dairies, laundries and other business organizations can use this service in communicating to and from their delivery vehicles.   Similarly, it can be used in communicating to and from the trucks, tractors, and other mobile units operating in and around large industrial plants and construction projects – many of which spread over a number of square miles.   It can be used on farms and ranches for communications to and from men in the fields; on board harbor and river craft; in mountain and swamp areas, etc.   Sportsmen and explorers can use it to maintain contact with camps and to decrease the hazards of hunting, fishing, boating, and mountain climbing.   Citizens generally will benefit from the convenience of this service by utilizing two-way portable radio equipment for short range private service between points where regular communication facilities are not available.   During emergencies when wire facilities are disrupted as a result of hurricane, flood, earthquake, or other disaster, the service, as has been demonstrated by the amateur service, will be of inestimable value.

The coverage that stations in this service will provide will, of course, be limited by the characteristics of the frequencies in the 460-470 Mc band.   It should also be noted that the purposes to which stations in this service may be put are not exclusive to this service.   For example, radiotelephone service to physicians’ cars may be provided by stations operating in the Citizens’ Radiocommunication Service in the 460-470 Mc band and may also be provided by stations in the General Mobile Service which are operated on lower frequencies.

The kinds of operations described above will require point-to-point, fixed point-to-mobile, mobile-to-mobile, and multiple-address communications.

In regard to the actual radio equipment to be used in this new service, the Commission proposes to assign no “communication channels” within the available band 460-470 Mc, intends to keep to a minimum its rules and regulations governing the service, and will rely upon the 10,000 kc width of the new band to provide reasonably interference-free operation in most parts of the United States.   The commission expects that the inevitable problems that will arise from interference in some localities will be satisfactorily resolved through the efforts of local cooperative groups of licensees.   Through such voluntary self-regulation, it is hoped that insofar as is practicable, the basic principles which are applied in the allocation of communication channels and the regulation of interference in established radio services will be applied also to the Citizen’s Radiocommunication Service in order that comparable results may be attained.

The principal test to be applied for type-approval of citizens’ radio transmitting equipment will be the determination of its ability to operate, under all practical service conditions, on a frequency or frequencies always within the allocated band 460-470 Mc. Information available to the Commission at this time regarding the carrier frequency stability that can be maintained in this service is not deemed conclusive, but is sufficient to justify the stipulation of initial proposals.   Estimates of such stability range from 1 per cent for the simpler types of self-oscillator transmitters (under conditions of A-0 emission) to 0.01 per cent for the better types of crystal-controlled transmitters.

Although the Commission desires to encourage use of the better class of equipment that will provide the most effective and reliable communication service, it is not unmindful of the relation between the degree of stability and the cost of construction.   While some of those who will operate stations in the Citizens’ Radiocommunication Service probably will employ the best obtainable equipment, regardless of cost, others will be able to use the service only if the selling price of the equipment is kept within the limit of their ability to pay.   Hence, to meet both the engineer’s objective of technical excellence and availability to the average citizen at a reasonable cost, the Commission proposes, through subsequent regulations to be adopted, that the band 460-470 Mc be used as follow:

• 460-462 Mc   -   Class A stations at fixed locations exclusively.

• 462-468 Mc   -   Class A and Class B stations.

• 468-470 Mc   -   Class A stations exclusively.

It is proposed that Class A stations be permitted a frequency tolerance of 0.02 per cent, whereas Class B stations would be given much wider latitude with a permissible tolerance of 0.2 per cent.   All Class B transmitters, however, would be initially adjusted by the manufacturer or the individual builder of composite equipment to operate within 0.2% per cent of the center-band frequency 465 Mc.   Subsequent deviation from this adjustment when in actual service would not be a violation of regulations provided the emission is confined within the sub-band 462-468 Mc.   If practical experience indicates that it is feasible and desirable to permit more latitude in the initial carrier frequency designation for Class B transmitters, the Commission plans to take such action.

Restriction of Class B stations to operation within the sub-band 462-468 Mc, while allowing the Class A stations to transmit on any frequency within the entire band, is intended to reduce interference to use of the facility by persons who can afford to obtain the more costly Class A transmitters.   Moreover, the proposed exclusive use of one end of the band (460-462 Mc) by Class A stations at fixed locations only should facilitate the more effective use of point-to-point communication, multiple-address systems, and systems of land stations serving an associated group of mobile units.   It is thought that the signals from such fixed stations could be received without being subjected to unexpected and transient interference from mobile stations.   The designation of specific channels for Class A stations will not be undertaken by the Commission; however, the Commission’s Staff will be available for consultation on this subject if it is desired to obtain constructive comment regarding the voluntary plans of cooperative licensee group.   Until evidence is shown that Class B stations should be permitted to change frequency intentionally, it will be expected that their operation will be confined to within 0.2 per cent of 465 Mc insofar as may be practicable in service.

   Additional transmitter type-approval tests are proposed to cover maximum permissible power-input, possible presence of superfluous emissions, and within of communication band.   In regard to “power”, it will be observed that under Section 324 of Communications Act of 1934, as amended, all radio stations must use the minimum amount of power necessary to carry out the communication desired; exception is made only with respect to communications or signals relating to vessels in distress.   Hence, the use of highly directive or “beam” transmitting antennas will be permitted on the premise that licensees will be cognizant of the statutory limitation on power; however, if this permission results in intolerable or unnecessary interference, the Commission will take such remedial action as may be appropriate.   All of the conventional types of emission are proposed to be authorized with the exception of type A-5 (television) inasmuch as the use of type A-5 emission would not appear to be practicable in this service.   Nevertheless, the regulatory procedure will provide for the possible granting of authority to use any type of emission, including A-5, if a satisfactory showing can be made as to the purpose to be served and the need therefore. Ordinarily, it is believed that a maximum communication band of 0.2 Mc will provide for all useful types of emission.

   While the Commission may take such measures as may be appropriate to prevent the widespread use of any type of receiving equipment in the Citizens’ Radiocommunication Service which unnecessarily radiates emissions that cause serious interference to radiocommunications, it does not propose at this time to apply “type-tests” to receiving equipment.   Instead, it proposes that manufacturers of receiving equipment voluntarily apply certain recommended tests to determine the existence of unnecessary emissions and cooperate with the Commission to avoid undesirable deterioration of the Citizens’ Radiocommunication Service that conceivably may result if this factor is neglected.

   The governmental approval of transmitting equipment prior to authorizing its operation under radio station license, and the subsequent promulgation of official notices of specific types of “approved” transmitters which are manufactured for distribution to the general public, is being proposed in the belief that this procedure will substantially reduce the difficulties to be expected in administration and enforcement of the operational phases of the Citizens’ Radiocommunication Service.

Requirements and Type Approval Tests for Equipment To Be Used in Citizens’ Radiocommunication Service

Ⅰ. General

Commission approval of transmitting equipment to be licensed in the Citizens’ Radiocommunication Service may be obtained either through “type approval” of a specific model produced by a manufacturer for ultimate distribution to the general public as set forth herein or through approval, in the course of processing the related application for station authorization, of any other specific type of unit in accordance with adequate technical information and showing of performance as required in such application.   If desired, the opinion of the Commission with respect to permissible radiation of emissions by receiving equipment may be obtained by request contingent upon examination and consideration of adequate technical information and showing of performance as contained in a formal written engineering report submitted to the Commission.

Approval by the Commission of transmitting equipment for use in the Citizens’ Radiocommunication Service is conditional upon compliance with the requirements hereinafter specified.   The use and availability of approved equipment in this service, however, is not to be construed as relieving the licensee from the responsibility of using and operating the station in accordance with all applicable rules and regulations of the Commission, in addition to all applicable provisions of law and treaty.

   In approving transmitting equipment as meeting these Requirements and Type Approval Test, the Commission recognizes that the specific type of equipment so approved has the inherent ability to function in compliance with the terms of a station license authorizing its use in the Citizens’ Radiocommunication Service, subject to any necessary periodic adjustment or maintenance by qualified persons.

No change whatever will be permitted in the physical construction, wiring, or equipment licensed in this service, except when the manufacturer, the station licensee, or other responsible person is specifically authorized by the Commission to make such change.   When it is desired to make any change in type approved or licensed equipment, an application therefore, together with all pertinent information, shall be submitted to the Commission for consideration and appropriate action.

Type approval of transmitting equipment for use in the Citizens’ Radiocommunication Service, when given by the Commission, will not be withdrawn unless required in the future as a measure necessary to conform with possible unforeseen changes in statute or treaty, or unless the equipment involved proves defective in service and cannot be relied upon to operate in accordance with the Commission’s rules and regulations.   Withdrawal of type approval means that no additional units of the type in question may be authorized for use in the Citizens’ Radiocommunication Service but will not apply to such units already licensed unless it is found that there has been an unauthorized change in design or construction of such licensed equipment.

Ⅱ. Basic Requirements

A. The transmitting equipment to be approved may consist of one or more units, either separate and distinct from each other or combined with each other and/or with other units for receiving;   or it may be incorporated in other equipment not used for transmitting or receiving in the Citizens’ Radiocommunication Service, if the particular arrangement is approved by the Commission.   Type approval, when given, will apply only to the transmitting equipment to be used in the Citizens’ Radiocommunication Service.

B. Controls for adjustment of the carrier frequency of the transmitter shall not be accessible from the exterior of any unit unless such accessibility is specifically approved by the Commission.

C. Any basic instructions concerning the proper adjustment of the equipment that may be necessary, and the correct indication of any instrument incorporated for the purpose of revealing improper operation, shall be briefly inscribed in a durable manner on the equipment in a position to be easily read by the operator.

D. A durable nameplate shall be mounted on each manufactured model for distribution to the general public showing the name of the manufacturer, the type and serial number, the FCC approval number, and the month and year of completion by the manufacturer.   However, this nameplate need not be provided on a working model submitted to the Commission for test and approval.

Ⅲ. General procedure in regard to testing and approval of transmitting equipment manufactured for distribution to the general public.

A. Formal written application for type approval of transmitting equipment intended to be manufactured for ultimate distribution to the general public may be made by a manufacturer to the Commission at Washington, D. C.   When advised by the Commission, the applicant for type approval must send a typical production model of the particular equipment to the Commission’s Laboratory at Laurel, Maryland, for test, and await an official report from the Commission.   In connection with such tests, the manufacturer shall supply all instructions and/or services which are intended to be supplied to the purchaser of the equipment, including a proposed instruction book.   Transportation of the equipment and associated documents to and from the Laboratory will be at no cost to the Government.

B. Failure to meet any test or requirement specified in this document may result, by direction of the Commission, in the discontinuance of all tests on the particular model involved and in the immediate rejection thereof by the Commission.

C. The tests prescribed in this document may be conducted by the Federal Communications Commission, and/or by any other cooperating government department, and if prescribed by the Commission shall be at the expense of the manufacturer submitting the equipment for approval.   An official report of the tests conducted by the Federal communications Commission, and/or other cooperating government department will be made available to the manufacturer involved.   Field tests, as deemed necessary or desirable by the Commission, may be carried out by authorized government personnel to determine the reliability of the equipment under operating conditions equivalent to those encountered in actual service.   Prior to approval or rejection of the equipment by the Commission, the results of these tests will be made known only to the responsible government officials and to the Commission for its consideration.

D. Transmitting equipment not constructed by a manufacturer for ultimate distribution to the general public will not be tested by Commission for type approval.   Such equipment must be described as required by the Commission in an application submitted for license to authorize its use in the Citizens’ radiocommunication Service.   In such instances, complete information shall be supplied showing that the equipment fully complies with either Class A or Class B Requirements of the Commission as proven by adequate tests conducted by a competent person or persons in accordance with the pertinent procedures herein set forth.

Ⅳ. Specific technical requirements for type approval of transmitting equipment

A. Operating frequency: Class A transmitters.

The transmitter shall be designed, constructed, and adjusted by the manufacturer to operate on a frequency or frequencies within the band of 460-470 Mc, subject to the condition that the communication band shall not at any time extend beyond the limits of the 460-470 Mc band.   Under all conditions of use in the Citizens’ Radiocommunication Service, the transmitter shall be inherently incapable of emitting electro-magnetic waves of interference field strength outside the band 460-470 Mc. In this respect, “interference field strength” means a field strength sufficient to actuate any type of radio receiving apparatus of modern design (as generally used in any authorized radio service) to an extent capable of causing interference or communications.   A test to determine compliance with this requirement will be made when the radio receiver with associated antenna system is located at any point not more than ten feet from the transmitting equipment under test, from any type of antenna connected to the transmitter and from any type of line connecting the transmitter to the antenna.

B. Operating frequency: Class B transmitters.

The transmitter shall be designed, constructed, and adjusted by the manufacturer to operate initially, under average conditions, within 0.2 percent of the frequency 465 Mc.   Under all conditions of use in the Citizens’ Radiocommunication Service, the transmitter shall be inherently incapable of emitting electro-magnetic waves of interference field strength outside the band 462-468 Mc. In this respect, “interference field strength” means a field strength sufficient to actuate any type of radio receiving apparatus of modern design (as used in any authorized radio service ) to an extent capable of causing interference to the reception of desired signals or communications.   A test to determine compliance with this requirement will be made when the radio receiver with associated antenna system is located at any point not more than ten feet from the transmitting equipment under test, from any type of antenna connected to the transmitter and from any type of line connecting the transmitter to the antenna.

C. Frequency stability: Class A and Class B transmitters.

The operating frequency at any time during the period of test shall not deviate more than 0.02 percent for Class A transmitters nor more than 0.2 percent for Class B transmitters from the operating frequency measured as soon as possible during the initial period of test operation, under any or all of the following test conditions:

1.   Gradual and sudden ambient temperature variations from 0 to 150 F.

2.   Barometric pressure variations corresponding to those from sea level to 12,000 feet above sea level.

3.   Relative ambient humidity from 5 to 95 per cent.

4.   Atmosphere containing high saline content such as encountered on oceans.

5.   Movement of objects in the immediate vicinity of the equipment under test.

6.   Power supply voltage variations normally to be encountered under actual operating conditions.

7.   Length of test periods to be equivalent to those which will be encountered under the most severe conditions of operation for which the unit may be used.

Whenever possible, the operating frequency shall be measured while the transmitting equipment under test is radiating type A-0 emission.

D. Maximum power: Class A and Class B transmitters.

The transmitting equipment shall be inherently incapable of operating at a power input of more than 50 watts to the anode (plate) circuit of the electron tubes which supply energy to the radiating system.

E. Emission: Class A and Class B transmitters.

The transmitter shall not be capable of producing emissions of any type other than A-0, A-1, A-2, A-3, A-4, or FM, unless it is shown after operation under an experimental license that another type of emission is necessary for a definite purpose in the Citizens’ Radiocommunications Service.   When radiating amplitude-modulated waves of any type, the percentage of modulation shall not exceed 100 at any time.   When radiating any type of authorized emission, including FM emission, the communication band of the emitted waves shall not exceed 0.2 Mc.

Ⅴ. Receivers – Recommended manufacturers’ tests to determine the possibility of interfering emissions.

Radio Receiving equipment, with or without associated antenna and connecting line between antenna and receiver, should be inherently incapable of emitting radio waves which have a field strength sufficient to actuate any type of radio receiver (as used in any authorized service) to an extent capable of causing interference to the reception of desired signals or communications.

This test shall be made when the receiver being utilized for possible interception of emissions radiated from the receiver under test is located at any point not more than ten feet from the latter receiver, from any type of antenna connected to such receiver, and from any type of line connecting such receiver to its antenna.

Controls for any adjustment of the receiver which might result, due to improper adjustment thereof, in the radiation of interfering emissions should not be accessible from the exterior of any unit.

Tests to determine compliance with this performance should be made by the manufacturer under conditions most favorable to the maximum radiation of emissions by the particular receiving equipment under test.

It is suggested that the results of these tests with respect to any type of receiver to be actually used in the Citizens’ Radiocommunication Service be made known to the Commission.